Strange artefacts / noise with some xbr shaders (Intel GPU)

[bidinou]

(I figured out it would probably be useful to file a bugreport for this problem I mentioned on the libretro forum, as it looks like a bug, maybe driver-related, I dunno :)

Hi everyone !

On 2 different setups, I encounter the very same issues with quite a few advanced shaders.

My machines are :

• 5 year old laptop with core i5, Ubuntu 16.04 64 bits, retroarch ppa (stable / testing used) Intel HD 3000
• current Intel NUC (Skylake), core i5, Iris 440 under Lakka

Quite a few shaders work perfectly.

With some shaders, there is a strange layer of "noise" above the picture. It is moving.

Here is a photograph showing the issue : https://postimg.org/image/wc7ja4rqj/ <-- with 4xbr-hybrid-crt https://postimg.org/image/uku2fz3pb/ <-- with xbr-lv3 I have a similar issue with the scalefx shader.

For instance, this issue doesn't appear with xbr-lv3-multipass or noblend.

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[hizzlekizzle]

Intel+mesa causes some weird noise on some GLSL shaders, like crt-royale currently.